Review "See the list below for shared expressions" (Markdown files)

[hhkaos]

We just noticed that several README.md files do not have all expressions listed under "See the list below for shared expressions." (some do not even have that statement, like the readme template indicates). Examples:

• https://github.com/Esri/arcade-expressions/tree/master/popup
• https://github.com/Esri/arcade-expressions/tree/master/dashboard_data

It would be great is someone could review and make sure all of them have a list of the provided expressions for easier navigation and discovery.